Oxidative Stress in Rat Cortical Neurons and Astrocytes Induced by Paraquat In Vitro
Oxidative Stress in Rat Cortical Neurons and Astrocytes Induced by Paraquat In Vitro
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DOI：
10.1080/10298420290007574
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发表时间：
2002-01-01
影响因子：
3.7
通讯作者：
Schlueter, G.
中科院分区：
文献类型：
--
作者：
Schmuck, G.;Roehrdanz, E.;Schlueter, G.
氧化应激被认为是成人大脑神经元细胞死亡的重要机制。然而，直到现在还不清楚神经元是否比大脑中的其他细胞（如星形胶质细胞）对氧化应激更敏感。因此，这两种细胞类型都暴露于氧化还原循环化合物百草枯引起的氧化应激。MTT和中性红两种不同的细胞毒性试验表明，皮质神经元对百草枯毒性比星形胶质细胞更敏感。线粒体功能由线粒体膜电位和细胞内ATP浓度决定。同样，皮质神经元受损更严重（百草枯比星形胶质细胞受损更严重）。暴露于百草枯后，皮层神经元中活性氧的产生比星形胶质细胞高得多，并且与细胞内谷胱甘肽（GSH）的消耗更高相关。脂质过氧化可以通过分解产物丙二醛（MDA）在星形胶质细胞中表现出来，而在皮质神经元中检测到4-羟基壬烯醛（4-HNE）作为终点。氧化应激是否以及如何影响抗氧化防御是通过抗氧化酶表达的变化来确定的。百草枯暴露导致星形胶质细胞过氧化氢酶、MnSOD和CuZnSOD mRNA表达增加2-3倍。与皮质神经元星形胶质细胞相比，百草枯处理后过氧化氢酶和MnSOD mRNA水平仅轻微升高约1.5倍。在百草枯暴露后，两种细胞类型中只有谷胱甘肽过氧化物酶（GPx） mRNA的表达水平没有变化。由此可见，抗氧化酶表达水平的显著增加可能使星形胶质细胞比神经元细胞更能抵抗氧化应激。
Oxidative stress has been discussed as crucial mechanism of neuronal cell death in the adult brain. However, it was not clear until now whether neurons are more sensitive to oxidative stress than the other cells in the brain, e.g. astrocytes. Therefore both cell types were exposed to oxidative stress provoked by the redox-cycling compound paraquat. Cortical neurons were found to be more sensitive towards paraquat toxicity than astrocytes as shown by MTT and Neutral Red assay, two different cytotoxicity assays. Mitochondrial functions were determined by the mitochondrial membrane potential and intracellular ATP concentrations. Again cortical neurons were more severely impaired (by paraquat than astrocytes). The production of reactive oxygen species after paraquat exposure was much higher in cortical neurons than in astrocytes and correlated with a higher depletion of GSH (intracellular glutathion). Lipid peroxidation could be shown in astrocytes via the breakdown product malondialdehyde (MDA) whereas in cortical neurons 4-hydroxynonenal (4-HNE) was detected as this endpoint.If and how oxidative stress influences the antioxidant defense was determined via changes in the expression of antioxidant enzymes. Paraquat exposure lead to a 2-3 fold increase of catalase, MnSOD and CuZnSOD mRNA expression in astrocytes. In contrast to astrocytes in cortical neurons catalase and MnSOD mRNA levels were only marginally elevated about 1.5-fold by treatment with paraquat. Expression levels of glutathione peroxidase (GPx) mRNA were the only one that were not changed in both cell types after paraquat exposure. It is concluded that the more marked increase in expression levels of antioxidant enzymes may render astrocytes more resistant to oxidative stress than neuronal cells.